1. Field of the Invention
The present invention relates to a portable apparatus and method of measuring a wireless channel and a multiple antenna correlation that may measure a wireless channel and an antenna correlation value indoors and outdoors in real time.
2. Description of Related Art
A next generation mobile communication system requires a high speed data rate to provide a variety of high-speed multimedia services beyond an existing voice and low-speed data service. Researches on various technologies such as a broadband frequency usage, a method of using a multiple antenna, and the like have been conducted to achieve a high speed data rate. A system using multiple antennas may be more sensitive to a characteristic of a wireless channel in comparison to a single antenna system in a conventional art. Accordingly, a characteristic of a wireless channel is required to be precisely ascertained when designing a multiple antenna system. To develop a next generation mobile communication system using multiple antennas, multiple receiving/transmission antennas are to be arranged to satisfy an optimum frequency efficiency in various mobile communication environments. That is, it is critical that a distance between antennas is appropriately set to enable an antenna correlation to be minimum, and to minimize an interference and attenuation. In particular, a next generation terminal such as a Personal Digital Assistant (PDA), a cellular phone, and the like where a radio Multiple Input Multiple Output (MIMO) antenna is mounted may be developed to be portable and small. A plurality of receiving antennas may be arranged to minimize a correlation among the plurality of receiving antennas in a limited Printed Circuit Board (PCB) of the above-described terminal. For this, an apparatus that may measure a wireless channel and an antenna correlation is required.
In a conventional art, a wireless channel measurement apparatus may be mostly for outdoors, and include a plurality of baseband modules, a high-power Radio Frequency (RF) module (transmission power over 3 watt on average), and a computer including a data storage device for control and analysis. Accordingly, power consumption, size, and weight of the wireless channel measurement apparatus may be significant. Thus, a vehicle may be required when measuring an outdoor wireless channel using the wireless channel measurement apparatus, and a cart may be required for movement when measuring an indoor wireless channel. In particular, when measuring a limited indoor space, for example, a reverberation chamber measurement, an anechoic chamber measurement, an indoor-to-outdoor movement measurement, an outdoor-to-indoor movement measurement, an indoor radio wave environment measurement, and high transmission power is not required and measurement may not be easily performed using the wireless channel measurement apparatus in the conventional art.
Also, a measurement apparatus requires a storage device to store information required to analyze a channel environment and compute a correlation. Since a significant amount of information is required for the correlation computation, a mass storage device with a capacity to store a large amount of measurement data may be required. Also, a large Liquid Crystal Display (LCD) to display a measurement result as a graph, and an input device to input information required for measurement may be required. Accordingly, a small measurement apparatus may not be provided.
Also, in a conventional art, to measure a wireless channel and an antenna correlation, a wireless channel is to be first measured using a wireless channel measurement apparatus, channel measurement data is to be separately backed up on a mobile storage device, and the channel measurement data is to be analyzed using a computer, which is a complex process. Accordingly, a measurement apparatus to measure an antenna correlation of terminal antenna pattern PCBs in a variety of indoor and outdoor environments including a reverberation chamber is required to develop a radio MIMO terminal.